1. Technical Field
The present disclosure relates to an arctic ship with a derrick, and more particularly, to an arctic ship with a derrick, which can stably maintain an internal environment of an enclosed derrick.
2. Description of the Related Art
Due to the rapid international industrialization and industrial development, the use of the earth's resources, such as oil, is gradually increasing. Accordingly, stable production and supply of oil is emerging as a very important worldwide issue.
For this reason, much attention has recently been paid to development of small marginal fields or deep-sea oil fields, which have been ignored because of their low economic feasibility. Therefore, with the development of offshore drilling techniques, drill ships equipped with drilling equipment suitable for development of such oil fields have been developed.
In conventional offshore drilling, rig ships or fixed type platforms have been mainly used, which can be moved only by tugboats and are anchored at a position on the sea using a mooring gear to conduct an oil drilling operation. In recent years, however, so-called drill ships have been developed and used for offshore drilling. The drill ships are provided with advanced drilling equipment and have structures similar to typical ships such that they can make a voyage using their own power. Since drill ships have to frequently move in order for development of small marginal fields, they are constructed to make a voyage using their own power, without assistance of tugboats.
FIG. 1 is a side view illustrating a conventional arctic ship which performs a drilling operation on the sea.
A moonpool 3 is formed at the center of a conventional arctic ship 1, such that a riser 4 or a drill pipe 5 is vertically movable through the moonpool 3. In addition, a derrick 2 in which a variety of drilling equipment is integrated is installed on a deck of the ship 1.
The conventional derrick 2 has an opened structure in which steel pipes are coupled together, like a power transmission tower installed on the ground. A crown block section in which a crown block is installed is formed at an upper portion of the derrick 2. The crown block section is formed in a conical shape that becomes narrower upwardly. In the case of the derrick having such an opened structure, natural ventilation is possible without any separate mechanical ventilating apparatus.
However, if the conventional derrick having the opened structure is installed in an arctic ship that sails around an arctic region, a variety of drilling equipment is exposed at below zero temperatures for a long time. Consequently, the drilling equipment may not operate normally. Also, due to the structural shape of the conical crown block section that becomes narrower upwardly, the worker's accessibility becomes weak.